The present invention relates to a voltage supply control device and voltage supply control method.
As disclosed in reference 1 (Japanese Patent Laid-Open No. 2003-189603), in a conventional WCDMA cellular phone terminal, the battery voltage is dropped by a DC/DC converter in the power supply device in accordance with transmission power. The voltage is dropped to such a level not to distort a signal and supplied to a power amplification circuit such as a power amplifier. With this method, the power added efficiency of the power amplifier is increased, and the current consumption is reduced.
However, if the battery voltage decreases in dropping the voltage by the DC/DC converter and supplying the voltage to the power amplifier, the current consumption of the DC/DC converter increases, and no necessary voltage can be supplied. As a result, the RF characteristic degrades.